1.  A criminal proceeding may not be commenced against any person who had not attained 18 years of age at the time of the alleged crime, except as the result of a finding of probable cause authorized by Title 15, section 3101, subsection 4, or in regard to the offenses over which juvenile courts have no jurisdiction, as provided in Title 15, section 3101, subsection 2.  

2.  When it appears that the defendant's age, at the time the crime charged was committed, may have been such that the court lacks jurisdiction by reason stated in subsection 1, the court shall hold a hearing on the matter and the burden shall be on the State to establish the court's jurisdiction, as defined by subsection 1, by a preponderance of the evidence.  

3.  Except as provided in subsections 1 and 2, when concurrent jurisdiction has been established pursuant to Title 15, section 3101, subsection 2, paragraph F, the Juvenile Court has exclusive original jurisdiction over a case involving a juvenile who is alleged to have committed a juvenile crime as defined in Title 15, section 3103, subsection 1.